Kommunikationsnetze I Kommun kat onsnetze I Communication

Kommun kat onsnetze I
Kommunikationsnetze
Communication Networks I
Prof. Dr. Carmelita Görg
Dr.-Ing. Bernd-Ludwig Wenning
Amanpreet Singh M.Sc.
M Sc
Dr.-Ing. Xi Li
Umar Toseef M.Sc.
Kommunikationsnetze
Communication
ommun cat on Networks
N twor s (ComNets)
( omN ts)
FB1/ITH/tzi – Universität Bremen
Raum S2260
0421 218 62365 -- Tel
T l
0421 218 98 62365 -- Fax
{{cg|wenn|xili|aps|umr}@comnets.uni-bremen.de
g
p
}
www.comnets.uni-bremen.de
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INTRO - 1
Contents (Inhaltsverzeichnis)
 D
Distributed Systems
y
m ((Verteilte Systeme)
y m )
 ISO/OSI Reference Model for Open System Interconnection
(Referenzmodell für offene Kommunikation)
7 Layer OSI Model (7 Schichten OSI-Modell)
 Formal Specification Methods for Protocols
(Formale Spezifikationsverfahren für Protokolle) (SDL)
 Performance Evaluation of Communication Networks
(Leistungsbewertung von Kommunikationsnetzen):
((Introduction
d
/ Einführung)
E f h
)
Probability Theory and Queuing Systems
(Wahrscheinlichkeitsrechnung
g und Warteräume)
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INTRO - 2
Contents (Inhaltsverzeichnis) (cont.)
(cont )
( ) Physical
(1)
y
Layer
y ((Bitübertragungsschicht,
g g
Physikalische
y
Schicht))
(2) Data Link Layer, Medium Access Control (Sicherungsschicht)
(3) Network Layer (Vermittlungsschicht)
(4) Transport Layer (Transportschicht)
(5-7) Application Layers (Anwendungsorientierte Schichten)
Local Area Networks (Lokale Netze)
Wide Area Networks (Weitverkehrsnetze)
Network Control (Netzsteuerung):
(virtual) connections ((virtuelle) Verbindungen)
Routing (Wegewahl)
Addressing (Adressierung)
Fl
Flow
Control
C t l (Fluss-Steuerung)
(Fl
St
)
 System Examples (Systembeispiele):
ISDN/B-ISDN/ATM, WLAN: IEEE 802.11b, TCP/IP








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INTRO - 3
References
 Martin Bossert, Markus Breitbach:
Digitale Netze — Funktionsgruppen digitaler Netze und
Systembeispiele, B.G. Teubner 1999,
ISBN 3-519-06191-0
 Bernhard Walke:
Kommunikationsnetze und Verkehrstheorie I + II
Dienste und Protokolle, Lehrstuhl Kommunikationsnetze,
Vorlesungsskript RWTH Aachen
 Jean Walrand: Communication Networks, A first course,
WCB/McGraw-Hill 1998, ISBN 0-256-17404-0
 Andrew
A d
S
S. T
Tanenbaum:
b
Computer Networks, Prentice Hall 1996,
ISBN 0-13 349945-6
 Ross/Kurose,
R /K
C
Computer
t Networking:
N t
ki
A Top
T Down
D
A
Approach,
h 4th
ed., Addison-Wesley, July 2007 (slides available)
 Internet:
Int n t: many
m n references,
f
n
some
m are given
i n on
n our web
b p
pages
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INTRO - 4
Introductory remarks
 PSTN (Public Switched Telephone Network)
provides connectivity for more than a billion
telephone sets
 Phone
Ph
network
k has
h changed:
h
d
1890: manual to automatic switching
After 1950: electro-mechanic to electronic
switching
End
E d 1980’
1980’s: analog
l to digital
d
l techniques
h
Beginning of the 1990’s: Digital Mobile
…
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5
6
Introductory remarks
Manual switching
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Cross bar switching
Introductory remarks
 Last two decades:
 Computer communication is increasing very rapidly,
in the local and wide area
 Mobile communication is becoming
more popular, for both voice and data
 Today:
 transition to VoIP, All – IP
 Tomorrow ??? Future Internet
 Non-IP, Content Centric Networks
 Internet of Things
 Network Virtualization
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7
Subscribers….
Subscribers
Inhabitants
(Jul. 2009)
E
Europe
G
Germany
US
W ld
World
491 Million
82 Million
307 Million
6.790 Billion
Fixed
Telephones
Mobile
Phones
Internet
Users
Source: https://www.cia.gov/library/publications/the-world-factbook
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INTRO - 8
Subscribers….
Subscribers
E
Europe
G
Germany
US
W ld
World
Inhabitants
(Jul. 2009)
491 Million
82 Million
307 Million
6.790 Billion
Fixed
Telephones
238 Million
(2005)
51 Million
(2008)
150 Million
(2008)
1.268 Billion
(2008)
Mobile
Phones
466 Million
(2005)
107 Million
(2008)
270 Million
(2008)
4.017
4
017 Billion
(2008)
Internet
U
Users
247 Million
(2006)
22 Million
(2008)
223 Million
(2008)
1.018 Billion
(2005)
22 Million
(2008)
315 Million
(2008)
-
Internet
Hosts
Source: https://www.cia.gov/library/publications/the-world-factbook
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INTRO - 9
Subscribers Mobile Networks (end 2009)
Country
y
China
India
USA
Germany
Mobile Subscribers
[Mill]
747
400
380
110
Growth/Monat
[Mill]
ca. 8
ca. 10
-
Penetration
45%
25%
90%
120%
Markets in China and India have the highest growth rates in mobile
network subscibers.
[Source: HF-Professoren Tagung Berlin 2010,
Kathrein / Roland Gabriel]]
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INTRO - 10
Research
Communication Networks
Future Communication
mm
Networks
for mobile and dynamic systems




Heterogeneous
H
t
N
Networks
t
k
Self-organizing Ad-hoc and Sensor Networks
Mobile Networks
Future Internet
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INTRO - 11
Research
 Fundamental
m
Research
 Industry Relevant Research
 Application of Advanced Communication Technology
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INTRO - 12
APPLICATIONS
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INTRO - 13
SFB 637 – Transfer Project
j
Intelligent Container
 Food Transport Logistics
 Surveillance during transport
o Wireless Sensor Network
o Communication Service Module
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1
xMOTION
 IST 5FP Project
j
(June 2002 – January
y 2004)
 lead by T-Systems, Germany (14 partners/6 countries)
 three scenarios – thematically different – but similar
in technical requirements
q
and therefore architecture:
•
•
•
Emergency Management
Teleambulance
Transport Surveillance
 Demonstrating: Usability of networks and the benefit
for involved end-users;
 Evaluating UMTS Testbed in Bremen from May 2003 on,
extensive QoS measurements
 ikom’s role:




Trial
T
i lL
Leader
d T
Teleambulance
l
b l
Communication Gateway
Expert Group Leader: Communication Networks, Mobile IP, Security
Technical Evaluation
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T h l i and
Technologies
d Applications
A li ti
iin C
CoCar
C
Applications
Example use
case
- Hazard warning
- Floating car data
- Emergency brake light
-…
Cellular communication system
- UMTS,, HSPA,, LTE
- Multimedia Broadcast Multicast Service
(MBMS)
y
((IMS))
- IP Multimedia Subsystem
- XML Web Service Interfaces
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What is wearable computing?
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17
Wearable Computing –
„PDA in a Vest“
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18
1 Firefighter
1.
Fi fi ht (Paris Fire Brigade)
 Increase
c ease the
e safety
sa e y of
o the
e firefighters
e g e s
 Effective coordination and communication
 Augmentation of human senses
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19
2. Wearable Computing in
Maintenance (EADS)
 Inspection,
Inspection Service and Repair
 Smart Wearable Manuals

context
t t sensitive,
iti
adaptive
d ti
 Authoring, gather information during
maintenance
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20
3. The Clinical Pathway
y
(Gespag)
Coordinate the medical staff on a ward
Access the controls of a medical device
during examination
Present process related data to the
physician
h i i
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21
4. Wearable Computing in Production
(
(Skoda)
)
Permanent access to process and
production information for the plant
management, the service staff, and
the assembly worker
E-Learning for workers assigned to
new products
products, new processes or new
tasks
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22
Communication Requirements
 Communication
mm
between mobile
m
workers and environment
m
 Communication to Personal Area Network
 Communication to Lifeline
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INTRO - 23
tzi show room
Selected Partners
Universität Tübingen
Lehrstuhl für
Rechnernetze
und Internet
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25
THE BEGINNING…
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Distributed Systems
(Verteilte Systeme)
 Distributed System:
y
m
 Several independent computers
with in principle different operating systems
 Connected through a network
 Supporting one or more applications
A
B
Point-to-point connection between A and B.
A dedicated link can be used to connect two computers.
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INTRO - 27
Communication Network (Kommunikationsnetz)
Definition:
f
Technical infrastructure
f
f
for information
f m
and
communication systems with the following elements:




End
E
d d
devices,
i
e.g., PC
PC, work
k station,
t ti
telephone,
t l h
printer
i t
Server for general tasks, e.g., data base server
Physical transmission media, e.g., cables
Network control (Netzsteuerung) and switching units
(Vermittlungseinrichtungen), e.g., PABX Private Automated
Branch Exchange
g ((Nebenstellenanlage),
g ) Routers
 Operating System Software, e.g., UNIX
 Networking Protocol Software,
Software e.g.,
e g TCP/IP
 Application Software, e.g., ftp: file transfer protocol
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INTRO - 28
Computer Engineering Objects
Computer
Architecture
Thematic classification:
Distributed
Di
t ib t d
Systems
Computer engineering can
be divided in three categories,
which are of the same
relevance for distributed
systems:
Operating
System
K
Kernel
l
1 C
1.
Computer
t Architecture
A hit t
2. Data Comm. Systems Architecture
3 Application and Operating Software
3.
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Structure
of comm.
comm
paths
Data
Communication
Systems
Architecture
INTRO - 29
Operating Software,
Compilers Databases
Compilers,
Standard User
Software
Type of Networks
 Private networks,, internal networks (p
(private Netze))
 Within one company or organization
 Geographically confined, one location of a company
 Global
Gl b l companywide
mp
id networks
t
k (unternehmensweite
( t
hm s it N
Netze),
t )
corporate networks
 Private branch exchange (Nebenstellenanlagen)
 LAN: Local Area Networks (lokale Netze)
 Public networks, external networks (öffentliche Netze)
 Public telephone network (Telefonnetz)
 IDN: Integrated Data Network (Integriertes Datennetz)
 ISDN: Integrated Services Digital Network
(Digitales Netz Integrierter Dienste)
 Internet
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INTRO - 30
Media (Medien)






Voice
Audio
Text
Graphics
Data
Video
((Sprache)
p
)
(Audio)
(Text)
(Graphik)
(Daten)
(Bewegtbilder)
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INTRO - 31
Types of Distributed Systems
 Load sharing
g (Lastverbund )): uniform utilization of resources
by distributing the work load to different computers
 Performance sharing (Leistungsverbund ): lower response times
by
y distributing
g one task as subtasks to different computers
p
 Communication sharing (Kommunikationsverbund ):
transfer of data (messages) to different locations
by installing, e.g., a mail service
 Data sharing (Datenverbund): better utilization of disks,
increased availability, increased safety
 Maintenance sharing (Wartungsverbund ):
faster and cheaper maintenance of different computers
 Function sharing (Funktionsverbund ): making different functions
available at different locations by allowing access to specialized
servers (supercomputers, transputers, vector computers)
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INTRO - 32
Network Topologies (Netztopologien)
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INTRO - 33
Network Topologies (Netztopologien)
Star (Stern)
Tree (Baum)
Ring
Bus
Satellite, Radio Cell
(Satellit, Funkzelle)
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INTRO - 34
Complete mesh,
((vollständig
llstä di
vernetzt)
American inventor
has a patent
Functionality of the OSI Layers
Application Layer
(Aufgaben der OSI-Schichten)
ideas
for a description
OSI: Open System
Interconnection
Presentation Layer
write letter
Translate from
English to German
Präsentationsschicht
read letter
ISO-Standard
Session Layer
German engineer
understands
patent
Anwendungsschicht
g
Sitzungsschicht
put letter in envelope,
address it and take it
to the post office
T
Transport
Layer
L
deliver and
open letter
Transportschicht
letter sorting
machine
letter sorting machine
letter sorting
machine
Network Layer
N t
Network
kL
Layer
N t hi ht
Netzschicht
letter is put in
mailbag
empty
mailbag
letter is put in
mailbag
empty
mailbag
Data Link Layer
Data Link Layer
Sicherungsschicht
Sicherungsschicht
mailbag is
unloaded from plane
mailbag is transferred
to truck
Physical Layer
Physikalische Schicht
mailbag is
transferred to plane
Physical Layer
plane
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INTRO - 35
truck
mailbag is unloaded
from truck
Physikalische Schicht
Amerikanischer
Erfinder hat
Patent
Application Layer
Deutscher
Ingenieur versteht
das Patent
Anwendungsschicht
g
Functionality of the OSI Layers
(Aufgaben der OSI-Schichten)
Überlegung
einer
Beschreibung
Presentation Layer
OSI: Open System Interconnection
Übersetzen vom
Englischen ins
Deutsche
Präsentationsschicht
Session Layer
Lesen
des
Briefes
Sitzungsschicht
Brief verpacken,
adressieren und
beim Postamt abg.
T
Transport
Layer
L
Brief
zustellen
und öffnen
Transportschicht
ISO-Standard
Schreiben eines
Briefes
Briefsortieranlage
Briefsortieranlage
Briefsortieranlage
Network Layer
N t
Network
kL
Layer
N t hi ht
Netzschicht
Verpacken des
Briefes in
Postsack
Datalink Layer
Postsack
in Flugzeug
verladen
Physical Layer
Datalink Layer
Verpacken
des Briefes
in Postsack
Sicherungsschicht
Postsack
aus Flugzeug
ausladen
Physical Layer
Postsack
in LKW
verladen
Physikalische Schicht
Postsack
ausleeren
Flugzeug
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INTRO - 36
Postsack
ausleeren
Sicherungsschicht
LKW
Postsack
aus LKW
ausladen
Physikalische Schicht
Functionality of OSI Layers
 7 Application
pp
Layer
y
(Anwendungsschicht)
 6 Presentation Layer
(Präsentationsschicht,
Präsentationsschicht Darstellungsschicht)
 5 Session Layer
(Sitzungsschicht)
 4 Transport Layer
(Transportschicht)
 3 Network Layer
(Vermittlungsschicht, Netzschicht)
 2 Data Link Layer
(Übermittlungsschicht,
Ü
Sicherungsschicht)
 1 Physical Layer
(Bitübertragungsschicht, physikalische Schicht)
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INTRO - 37
Services Primitives and Communication of Peer-to-Peer Entities
(Dienstprimitive und Kommunikation von Peer-Entity zu Peer-Entity)
Entity
Request
q
Peer-to-PeerCommunication
Confirm
E tit
Entity
Indication
L
Layer
N
(Schicht N)
Response
p
Layers 1 to (N-1)
(Schichten 1 bis (N-1))
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INTRO - 38
Service Primitives
Primitive
Meaning
Request
q
An entity
y wants the service to do some
work
Indication
An entity is informed about an event
Response
An entity responds to an event
Confirm
The response to an earlier request has
come back
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INTRO - 39
Example of a simple connection-oriented
service with corresponding service primitives
1. CONNECT.request – Request a connection to be established
2. CONNECT.indication – Signal the called party
3 CONNECT.response
3.
CONNECT
– Used
U d by
b the
th called
ll d to
t accept/reject
t/ j t th
the
call
4. CONNECT.confirm – Tell the caller whether the call was
accepted
5. DATA.request
5
DATA request – Request to send data
6. DATA.indication – Signal the arrival of data
7. DISCONNECT.request – Request that a connection be released
8. DISCONNECT.indication – signal the peer about the request
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INTRO - 40
Analogy with the telephone system
1.
2.
3.
4.
5.
6
6.
7.
CONNECT.request
q
CONNECT.indication
CONNECT.response
CONNECT.confirm
DATA.request
DATA indication
DATA.indication
DATA.request
Dial Aunt Millie‘s p
phone number
m
Her phone rings
She picks up the phone
You hear the ringing stop
You invite her for tea.
She hears your invitation
She says she would be
delighted to come
…
8. DISCONNECT.request
You hang up the phone
9 DISCONNECT.indication
9.
DISCONNECT indication She hears it and hangs up too.
too
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INTRO - 41
Protocol (Protokoll)
 Protocol (Protokoll)
a formal description of message formats
(PDU: Protocol Data Units, Protokoll-Dateneinheiten)
and the rules two or m
more machines
m
must
m
follow
f
to exchange
g
those messages
e.g.: TCP: Transport Control Protocol, IP: Internet Protocol
Protocols
P
l usually
ll exist in two forms:
f
 First, they exist in a textual form for humans to
understand.
E g the majority of Internet protocols are distributed as
E.g.
RFCs (Request for Comments), which can (and should) be
read to understand the protocols' design and operation.
y exist as formal descriptions
p
or programming
p g
g
 Second, they
code
d f
for computers to understand.
d
d B
Both
h forms
f
should
h ld
ultimately specify the precise interpretation of every bit of
every message exchanged across a network. Standardization
Committees: ITU,, ETSI etc. (IETF)
(
)
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INTRO - 42
What are protocols ?
 Networking software is organized as protocols
 Eg:
E Human
H
protocoll vs network
k protocol:
l
Hi
TCP connection
req.
Hi
TCP connection
reply.
l
When
h are
you ready ?
Get http://www.rpi.edu/index.htm
2:00
<file>
time
http://www.ecse.rpi.edu/Homepages/shivkuma/teaching/video_index.html#ccn_foils
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INTRO - 43
Protocol Implementations
p
 Are building blocks of a network architecture
 Each protocol object has two different interfaces
 service interface: defines operations on this protocol
 peer-to-peer interface: defines messages exchanged with peer
Li+1
Li+1
service
i iinterface
t f
service
i iinterface
t f
Li
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peer interface
INTRO - 44
Li
Protocol Description
 Protocols can be described by
 extended finite state machines (erweiterte endliche Automaten)
with state changes depending on variables,
e.g., time dependent.
y state (Zustand) can be described by
y a set of variables.
Every
 by a formal specification language,
e.g., SDL (Specification and Description Language)
 Protocols are described by
 Syntax: defines syntactical units, e.g., sequence of characters
 Semantics (Semantik): describes the meaning and usage of
syntactically correct constructs
 Pragmatics (Pragmatik): information and knowledge about the
effects of actions
 Timing requirements (Zeitvorgaben): e
e.g.,
g timeouts,
timeouts
are a main part of protocols to guarantee the synchronization
of the communicating protocol state machines, e.g., after
transmission errors
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INTRO - 45
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INTRO - 46
Interface (Schnittstelle)
 Interface
f
(Schnittstelle)
describes signals (Signale), signal combinations
(Signalkombinationen), and timing requirements (Zeitgesetze)
that enter and leave a protocol executing entity.
entity
e.g.: V.24, serial interface (serielle Schnittstelle),
MMI: Man Machine Interface (Mensch-Maschine-Schnittstelle)
Protocols and interfaces always exist together.
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INTRO - 47
Standardization
(Standardisierung)
UN
U i d Nations
United
N i
ITU
IEC
ISO
International
Telecommunications
U i (1866)
Union
International
Electrotechnical
C
Commission
i i
International
Standardisation
O
Organisation
i i
ITU-R
CCIR
Comitée Consultatif
International
Radio
ITU-T
CCITT
Comitée Consultatif
International des
Télegrafes et Télephones
IRFB
CISPR
C
S
International
Frequency
Registration Board
Comitée International
Special Perturbance
Radio
WRC
World
Radiocommunication
Conference
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INTRO - 48
CEC
ITSTC
Commission of the
European Communities
Information Technology
Steering Committee
CEPT
CEN
Conference
C
f
off European
Postal and Telecommun.
Administrations
Comitée Européen
de Normalisation
ETSI
European Telecommun.
E
Tl
Standards Institute
GSM
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DECT
UMTS
INTRO - 49
CENELEC
Comitée
C
i é Européen
E
é de
d
Normalisation
Electrotechnique
Standardization in Europe
(Standardisierung in Europa)